Feed mechanism for marking machine

Abstract

A marking machine for marking metal nameplates, tags or the like. The marking machine employs a work table supported on a carriage which is movable into contact with a marking wheel to perform a printing operation. Improved advancing means are provided for the work table utilizing a feed pawl link having a pair of pivot points. One pivot point is connected to a feed link while the second pivot point is connected to a drag link moveable between upper and lower stops in a carriage casting. A bottom pivot point of the drag link is provided with a friction clutch on a pivot connected otherwise to a stationary portion of the machine. An improved feed rack is further provided which is polygonal in cross-section and may have different spaced teeth on each side for selective spacing. Half-spacing adjustment means are provided whereby the feed rack may be moved axially a half-space to change the spacing on the work table. An improved carriage release is furhter provided which comprises a control member pivoted on the same pivot as the pivotable feed link and engageable with the feed link to cause the feed pawl to move both of its teeth out of engagement with the feed rack to provide for manual movement of the work table as desired.

What is claimed is: 
     
       1. In a marking machine having a vertically moveable carriage supporting a transversely moveable work table supporting a workpiece to be marked by marking characters, said table being transversely moveable with respect to said carriage to advance the workpiece as it is being marked, table advancing means comprising a toothed rack having a series of teeth equi-distantly spaced along a side of the rack and pawl means engageable with said rack for advancing the table the distance between adjacent teeth for each marking operation, the improvement comprising said pawl means including a feed pawl having a pair of teeth engageable with the teeth in said rack, said pawl being pivoted at one end to a feed link member operable to pivot one end of the pawl and pivoted at a second end to a drag member operable to pivot a second end of the feed pawl about a moveable pivot member, limit guide means on said carriage defining upper and lower stops for said pivot member as the carriage is raised and lowered and friction clutch means on said drag member permitting the drag member to move responsive to contact of the limit guide means with the moveable pivot member. 
     
     
       2. The marking machine of claim 1, in which said feed link member is biased by a biasing means to urge the pawl into engagement with said rack. 
     
     
       3. The marking machine of claim 2, in which said friction clutch is operable to exceed the force of said biasing means and yield to contact by said limit guide means. 
     
     
       4. The marking machine of claim 2, in which a work table release is provided, said release comprising a pivotable operating shaft having a contact member engageable with said feed link member to pivot the feed pawl out of engagement with the feed rack and means biasing the operating shaft to hold said contact member out of engagement with said feed link member until said operating shaft is manually engaged, said contact member being engageable with said feed link member to overcome the force of said biasing means. 
     
     
       5. The marking machine of claim 4, in which the operating shaft is provided with an adjustable stop member limiting the movement of said shaft against the means biasing the operating shaft. 
     
     
       6. The marking machine of claim 1, in which said drag member is pivotally connected to a stationary part of the machine and said friction clutch means is adjustably engageable with said last named pivot connection. 
     
     
       7. The marking machine of claim 6, in which said last named pivot connection comprises a stationary pivot pin engageable in slot provided in said drag member and said friction clutch means comprising adjustable engaging elements for slidably fastening the drag member to the pivot pin. 
     
     
       8. The marking machine of claim 1, in which the drag member is pivotally connected to the pawl by a pivot pin having an extension element and said guide means comprises a slot in the carriage receiving said extension element and having upper and lower side walls limiting vertical movement of said extension element. 
     
     
       9. The marking machine of claim 1, in which the feed link member is pivoted to the pawl at a pivot point fixed to said carriage and the drag member is pivoted to the pawl at a pivot point freely moveable with respect to said carriage subject to engagement by said limit guide means. 
     
     
       10. The marking machine of claim 9, in which a work table release is provided, said release comprising a pivotable operating shaft having a contact member engageable with said feed link member to pivot the feed pawl out of engagement with the feed rack and means biasing the operating shaft to hold said contact member out of engagement with said feed link member until said operating shaft is manually engaged, said operating shaft being pivotable on a pivot pin connected to said carriage and forming the pivot connection for said feed link member. 
     
     
       11. The marking machine of claim 1, in which a work table release is provided, said release comprising a pivotable operating shaft having a contact member engageable with said feed link member to pivot the feed pawl out of engagement with the feed rack and means biasing the operating shaft to hold said contact member out of engagement with said feed link member until said operating shaft is manually engaged. 
     
     
       12. The marking machine of claim 1, in which the carriage is provided with a transversely extending guide shaft supporting said work table for transverse movement thereon, said work table having linear ball bearing means circumferentially girdling a portion of said shaft to provide for low friction sliding movement of said work table as it is advanced.